What a two-mile amenity count can and cannot see
A number that says "seven grocery stores within two miles" sounds precise. It is measuring something real, but not quite the thing most people assume, and the gap between the two is worth ten minutes of your time.
The amenities score on this site is built from counts: how many grocery stores, restaurants and cafés, parks, gyms, healthcare locations, shops and transit stops sit within two miles of a town's centre point. The data is OpenStreetMap, the same map a great deal of the world's navigation runs on, and the counting rule is identical in every town in the index.
That last part is what makes the comparison fair, and it is worth being precise about what it is fair about.
Two miles from a point, in a straight line
Every town is measured from a single centre point, and the radius is drawn as the crow flies. A shop two miles away across a river with no bridge counts exactly the same as a shop two miles away down a straight road. So does one on the far side of a motorway with no crossing.
For most suburbs this is a small distortion. For a town split by water, a rail corridor or a canyon, it is not, and the count will read better than the place feels. If a town's geography looks awkward on a map, treat its count as an upper bound.
A single centre point also flattens long, thin towns. Somewhere stretching six miles along a highway has one centre and two ends, and the ends are not two miles from anything the count knows about.
The map is drawn by volunteers
OpenStreetMap is made by people, mostly local, mapping what they know. Coverage is excellent in some places and patchy in others, and it is not patchy at random: dense, well-mapped areas attract more mappers.
So a low count can mean "there is little here" or it can mean "nobody has mapped what is here". The two look identical in the data. In practice the categories that matter most — supermarkets, parks, schools, hospitals — are among the best-mapped things in the database, and small independent businesses are the worst. A town's restaurant count is more likely to be understated than its grocery count.
The count is reliable at distinguishing "nothing within two miles" from "plenty within two miles". It is unreliable at ranking two places that both have plenty.
A count is not a quality, and not a walk
Eighty restaurants within two miles can be a high street you can walk along, or eight strip malls you have to drive between. The count cannot tell the difference, and neither can any other free national dataset — which is why walkability is one of the twelve questions this site puts to residents rather than something it claims to have measured.
The same applies to transit. The transit figure counts stops per square mile: a bus stop served four times a day counts exactly as much as one served every ten minutes. Frequency data exists in the form of published timetables, but not in a form that can be collected uniformly for every town in the country, so the honest thing is to say that the number counts posts in the ground and leave it there.
How to use it
Use it to sort. A suburb with two groceries, three parks and ninety restaurants within two miles is a materially different place from one with none of any, and the count will never get that distinction wrong.
Then stop using it. Between two towns that both score well, the count has nothing left to say, and the answer lives in things it cannot see: whether the shops are somewhere you would actually go, whether you can get to them without the car, and whether the place feels like anywhere on a Tuesday evening. That is what the resident poll is for, and failing that, an afternoon there.